1. Technical Field
The present invention relates to a piezoelectric actuator driven by deforming a piezoelectric layer, and to a liquid transfer device having such a piezoelectric actuator.
2. Description of Related Art
In a liquid transfer device described in Japanese Patent Application Laid-Open No. 2008-265353, a piezoelectric actuator is arranged at an upper face of a flow passage unit, and the piezoelectric actuator has: a vibration plate that is located so as to cover a plurality of pressure chambers, and that also serves as a common electrode; a piezoelectric layer located at an upper face of the vibration plate; and a plurality of individual electrodes each formed on an upper face of the piezoelectric layer, which is opposed to the plurality of pressure chambers. A region of the piezoelectric layer, sandwiched between each individual electrode and the vibration plate serving as the common electrode, is polarized in the thickness direction of this region. Then, upon application of a driving potential to the individual electrodes, an electric field whose direction is equal to the polarization direction is generated in the region of the piezoelectric layer sandwiched between the individual electrodes and the vibration plate, thereby causing the sandwiched region of the piezoelectric layer to be horizontally shrunk. Thus, the regions of the vibration plate and the piezoelectric layer opposed to the pressure chambers are wholly deformed into a convex shape toward the pressure chambers (i.e., unimorph deformation is caused), and the volumetric capacities of the pressure chambers are reduced due to this deformation, thereby increasing the pressure of ink inside the pressure chambers and ejecting the ink from nozzles communicated with the pressure chambers.